Root temp vs air temp

[smokinjoe1952]

As mentioned in my previous post, my struggling orchids made a surprising recovery when the s/h pots were placed on a seedling heat pad. So here is what I am thinking:

1. A night time air temperature ALL YEAR LONG of 66-69 is TOO cold, especially for all orchids in s/h, and especially for those that like "warm feet"

2. Plants that have done OK, but not super, would also benefit from the seedling mat, given the year round night temperatures. I.E. cat. and onc.


I have measured daytime temps when the chamber ambient is at 79, and water reservoir of 90 for those orchids on the heat mat. I am not sure what the roots would see a couple inches above the water, but obviously "in water" roots will see 90 degrees.

Maybe I should:

Shut heat mats off during the day when the lights are on, and the temps rise to 75+??

Increase the temperature of night time chamber air temps??

This might be a breakthrough discovery for increasing the health of my plants, so would sure like the experienced folks feedback.

Joe

[Ray]

If you want your plants to grow their best, you need to give them everything they have evolved to expect.

Most phalaenopsis, for example, are truly "hot growers" that would rarely see below 70°F in their entire lives, and thrive in triple digits with lots of shade and water. Grow them in the upper 60's and they might tolerate it, but won't be happy. Add the evaporative cooling of a semi-hydro pot in an low-RH environment and you're pushing them into a physiologically-damaging range.

Placing them on a heat mat may compensate to a degree, but if you grew them in warm, humid conditions, they'd be fine as-is.

[smokinjoe1952]

The "humid" is covered, and now that I have 3 heat mats running 24/7, the night temp only drops to about 72ish. Daytime up to 80 now, and RH 67day - 80night. What I am trying to decide, or should I say experiment with, is to determine if this overall warmer environment will be detrimental or incrementally better for the other species which include cats oncs paphs phrags miltoniopsis. Maybe I should only have a select few species that thrive on the chamber environment. But, I can control to a large extent what that environment is regarding heat, light and RH.

[Ray]

The assortment of genera you mention require an assortment of conditions, as well. Trying to grow them all the same will lead to failures.

[smokinjoe1952]

Ok, I would agree based on my experience so far. I have 2 shelves that both have dimmable LED strips, and I have my Cats and Oncs on the high light shelf, and the others on the low light shelf, with the low light shelf sporting a strip of shade cloth to reduce part of the shelf light even further. In your opinion, what listed genera would NOT work 68-72 night and 78-82 day and high humidity all the time with the proper light?

The grow chamber is in a small room in the lower level of our home, such that during the fall for a couple of weeks, I can crack a window open so the temp drops to 55 or so at night. That seemed to help the Cat's bloom, although I have read where that is not necessary for them.

I guess the king of suggestion I am looking for is something like:

Raise your night and day time temps to ~70N and ~80D, your high RH is fine for all genera, make sure you have and orchid under the right amount of light and lose the Milt. as it is a cool growing plant.

BTW - Also, have plenty of air circulation, but not too much as that caused desiccation on the higher up roots.

[Ray]

All of those plants will benefit from higher humidity.

You need to do some research about the growing needs of those plants. For example, phalaenopsis prefer very warm to hot conditions, while the miltoniopsis will do best if kept considerably cooler. Everything else you mentioned will be somewhere in-between.